Characterizing the interplay between multiplelevels of organization within bacterial sigma factorregulatory networks

摘要

Bacteria contain multiple sigma factors, each targeting diverse, but often overlapping sets ofpromoters, thereby forming a complex network. The layout and deployment of such a sigmafactor network directly impacts global transcriptional regulation and ultimately dictates thephenotype. Here we integrate multi-omic data sets to determine the topology, the operational,and functional states of the sigma factor network in Geobacter sulfurreducens, revealinga unique network topology of interacting sigma factors. Analysis of the operational state ofthe sigma factor network shows a highly modular structure with sN being the major regulatorof energy metabolism. Surprisingly, the functional state of the network during the two mostdivergent growth conditions is nearly static, with sigma factor binding profiles almostinvariant to environmental stimuli. This first comprehensive elucidation of the interplaybetween different levels of the sigma factor network organization is fundamental tocharacterize transcriptional regulatory mechanisms in bacteria.